Polyacetal is an engineering plastic which is excellent in mechanical physical properties, heat resistance, chemical resistance, and electrical properties, and has been widely used in the fields of, for example, electric devices, automobiles, machines, and building materials. Further, polyacetal can be formed into fibers, and therefore is being applied to the use as industrial materials, such as a brush and a filter, for which the mechanical strength, heat resistance, and chemical resistance that are advantageous properties of the polyacetal can be utilized (see, for example, Patent Literatures 1 to 3, and Non Patent Literature 1).
Recently, with respect to the material for underclothes for summer and sheets for bedclothes, studies have been made on a cloth having excellent contact cold sensation, which causes skins to feel cool when wearing or touching the cloth, giving them a sensation of coolness. For example, a cloth using a general material for cloth such as cotton and polyester fibers, e.g., PET, is disadvantageous in that fabric of the cloth itself exhibits only unsatisfactory contact cold sensation. Therefore, for the purpose of achieving the cloth having excellent contact cold sensation, there have been proposed a method in which an improved water absorption property is imparted to the fiber constituting the cloth, and a method in which an improved thermal conductivity is imparted to the fiber (see, for example, Patent Literature 4).